ubuntu 12.04 apt-get update出现错误

ubuntu 12.04 apt-get update出现错误如下
Ign http://mirrors.163.com jaunty-updates/universe Translation-en_US            
Ign http://mirrors.163.com jaunty-updates/restricted Translation-en_US          
Fetched 6,338 kB in 11s (562 kB/s)                                              
W: Failed to fetch http://mirrors.163.com/ubuntu/dists/jaunty-updates/main/source/Sources  404  Not Found [IP: 123.58.173.185 80]


W: Failed to fetch http://mirrors.163.com/ubuntu/dists/jaunty-updates/restricted/source/Sources  404  Not Found [IP: 123.58.173.186 80]


W: Failed to fetch http://mirrors.163.com/ubuntu/dists/jaunty-updates/universe/source/Sources  404  Not Found [IP: 123.58.173.186 80]


W: Failed to fetch http://mirrors.163.com/ubuntu/dists/jaunty-updates/multiverse/source/Sources  404  Not Found [IP: 123.58.173.186 80]


E: Some index files failed to download. They have been ignored, or old ones used instead.




办法:
vim /etc/resolv.conf 
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 8.8.8.8
search localdomain


sudo apt-get update
sudo apt-get upgrade